Two-dimensional weak radiation detector

ABSTRACT

A weak light detector ( 40 ) which can detect two-dimensional weak radiation at a high speed with high precision. The fluorescence from the DNA chip ( 46 ) is incident on a detection part ( 56 ) of a detection unit ( 52 ). The detection unit ( 56 ) has a detection module with a number of detection transistors being placed to correspond to cells of the DNA chip ( 46 ). The detection part ( 56 ) performs photoelectric conversion of the incident fluorescence (photon) to emit electrons, and amplifies the electrons to make them incident on the detection module. The detection transistors are switched based the Hadamard matrix to operate. A data processing unit ( 54 ) reads an output signal of the detection part ( 56 ), then performs Hadamard inversion, and determines the detection transistor which outputs the signal.

TECHNICAL FIELD

The present invention relates to a two-dimensional weak radiationdetector that detects weak electromagnetic waves and corpuscular rays,which are radiated two-dimensionally.

BACKGROUND ART

Recently, much attention is paid to an in situ hybridization by a DNAchip to perform prevention and diagnosis of diseases. This is made byplacing a fragment (cells) of a specified site of DNA in a matrix formon a glass base plate. The DNA chip is used in determining whether atested person has a gene related to a specified disease or not by addinga fluorescent material to a sample such as blood that is extracted fromthe tested person to label the DNA of the sample, and bringing thesample and the cells on the DNA chip in contact with each other toperform hybridization, and the like.

Conventionally, when it is detected with which cell of the DNA chip theDNA in the sample creates a hybrid, a device called a DNA chip reader asshown in FIG. 11 is used to detect it. The DNA chip reader 10 is aso-called confocal type, and includes a laser light source 14 forirradiating a DNA chip (specimen) 12 placed on an inspection stage notirradiated with laser light. A condenser lens 16 and a pin-hall 18 areplaced in series under the laser light source 14 to concentrate a laserbeam 21 emitted by the laser light source 14.

The laser beam 21, which passes through the pin-hole 18, is transmittedthrough a dichroic mirror 22 to separate fluorescence emitted from theDNA chip 12 and the laser beam 21, and thereafter, it is made parallellight by a collimate lens 24. After the laser beam 21, which is madeparallel light by the collimate lens 24, is reflected by a pair ofgalvano mirrors 26 and 28, it is incident on an objective lens 30, andconverges on the DNA chip 12 to irradiate to the cells. The galvanomirrors 26 and 28 are for scan-running the laser beam 21 along a surfaceof the DNA chip 12, and for example, when the galvano mirror 26 isrotated, the laser beam 21 moves in an X-direction on the surface of theDNA chip 12, and when the galvano mirror 28 is rotated, the laser beam21 moves in a Y-direction. Accordingly, by controlling the rotation ofthe galvano mirrors 26 and 28, the laser beam 21 can irradiate tooptional cells placed in the matrix form on the DNA chip 12.

When the cell of the DNA chip 12 creates a hybrid with the DNA in thesample labeled by the fluorescent material, it emits fluorescence whenit is irradiated with the laser beam 21. The fluorescence emitted fromthis cell is incident on the dichroic mirror 22 via the objective lens30, the galvano mirrors 28 and 26, and the collimate lens 24. Thedichroic mirror 22 selectively deflects only the incident fluorescenceat 90 degrees to make it incident on the photoelectron multiplier tube34 via the pin-hole 32. The photoelectron multiplier tube 34 generatesphotoelectrons with the incident fluorescence, and amplifies them tooutput them as a voltage pulse. Accordingly, by monitoring the output ofthe photoelectron multiplier tube 34, it can be known which cell of theDNA chip 12 emits the fluorescence, that is, it can be known that thegene that creates a hybrid with that cell is included in the sample.

However, the above-described conventional DNA chip reader 10 needs toscan the surface of the DNA chip 12 by moving the laser beam 21 in astep form. For this reason, when the laser beam 21 is scan-moved alongthe surface of the DNA chip 12 in which N×N of cells are placed in amatrix form, the scanning time is increased exponentially when thenumber of N increases to 100 to 1000 (the number of cells is tenthousand to a million), and thus tremendous time is required to read theinformation of the cells. Consequently, there is a trial to placemultiple photoelectric multiplier tubes 34 in a plane, irradiate theentire DNA chip 12 with a laser beam, and read output pulse of each ofthe photoelectric multiplier tubes 34 at once to obtain two-dimensionalinformation, but this is not realistic because the photoelectronmultiplier tube 34 is expensive and a large installation space isrequired.

It is considered to use a CCD type photon counting video camera toobtain the position of the cell, which creates a hybrid of the DNA chip12 two-dimensionally. The CCD type photon counting video camera performsphotoelectric conversion of incident photons to generate photoelectrons,amplifies a photoelectron in the number of electrons in each capillary(channel) by a secondary electron amplification, called a microchannelplate (MCP) constituted by a number of capillaries (capillaries), makethem incident on the fluorescent material again to convert the electronsinto light, and receive the converted light with the CCD video camera.However, when the CCD type photon counting video camera is used, thefollowing problem arises.

The processing of the photon counting mode is performed for a signalfrom the CCD video camera. Namely, an output signal of the CCD element,which corresponds to each pixel (pixel) of the CCD video camera isbinarized, and the output signals (the number of incident photons) perunit time are counted. However, readout of the output signals for eachelement of the CCD video camera is no more than about 100 times/s.

On the other hand, the fluorescence occurring from the cells of the DNAchip 12 is extremely weak, and photons are rarely incident on eachchannel (capillary) of the MCP. In addition, the duration of the pulseof the electrons incident on the CCD element from the MCP is 0.1 to 10ns, which is exceedingly short. Consequently, each element of the CCDvideo camera integrates the pulse of the electrons corresponding to theincident photons that rarely come for about 10 ms being a read cycle ofthe signal, which is 10⁶ to 10⁸ times as long as the pulse duration ofthe electrons. However, the CCD has a noise called a dark current, thisnoise is also integrated during the read cycle, and the detection systemcannot be realized unless the S/N of the pulse is 10⁶ to 10⁸ or more,which is unpractical.

The present invention is made to eliminate the disadvantages of theaforementioned prior art, and has its object to make it possible todetect two-dimensional weak radiation at a high speed with highprecision.

The present invention has another object to make it possible to obtain atwo-dimensional color image based on weak radiation with ease.

DISCLOSURE OF THE INVENTION

In order to attain the above-described object, a two-dimensional weakradiation detector according to the present invention is characterizedby having a photoelectric conversion part which emits electrons byincidence of photons, an amplification module which is placed to facethe photoelectric conversion part, and is provided with a number ofelectron amplification parts that amplify the electrons emitted by thephotoelectric conversion part, a detection module which is provided tocorrespond to each of the aforementioned electron amplification partsconstituting the amplification module, and is provided with a number ofelectron detection parts on which the electrons from the electronamplification parts are incident, an operation control part whichoperates each of the aforementioned electron detection partsconstituting the detection module based on an orthogonal modulationpattern, and a light incidence position calculation part which obtainspositions of the aforementioned photons incident on the aforementionedphotoelectric conversion part based on a control signal of the operationcontrol part and an output signal of each of the aforementioned electrondetection parts.

Further, a two-dimensional weak radiation detector according to thepresent invention is characterized by having a photoelectric conversionpart which emits electrons by incidence of photons, an amplificationmodule which is placed to face the photoelectric conversion part, and isprovided with a number of electron amplification parts that amplify theelectrons emitted by the photoelectric conversion part, a detectionmodule which is provided to correspond to each of the aforementionedelectron amplification parts constituting the amplification module, andis provided with a number of electron detection parts on which theelectrons from the electron amplification parts are incident, anoperation control part which operates each of the aforementionedelectron detection parts constituting the detection module based on anorthogonal modulation pattern; a light incidence position calculationpart which obtains positions of the aforementioned photons incident onthe aforementioned photoelectric conversion part, based on a controlsignal of the operation control part and an output signal of each of theaforementioned electron detection parts, and a wavelength calculationpart which obtains energy of the aforementioned photons based onmagnitude of the output signal of each of the aforementioned electrondetection parts, and converts it into a color signal.

The wavelength calculation part can be constituted to obtain themagnitude of the output signal based on repetition frequency of outputpulse signal of the aforementioned electron detection part and convertit into the aforementioned color signal. An emission part, which emitsphotons by incidence of microwaves or corpuscular rays, may be providedat a front of the photoelectric conversion part.

In the present invention constituted as described above, the photonscaused by weak radiation is converted into photoelectrons by thephotoelectric conversion part, and after the photoelectrons (electrons)are amplified in number in the amplification module, they are incidenton the detection module. The detection module is provided with theelectron detection parts corresponding to a number of electronamplification parts of the amplification module, and the electrondetection parts are operated according to the orthogonal modulationpattern (for example, the pattern corresponding to each line of theHadamard matrix being a binary orthogonal modulation pattern).Accordingly, the output signals (data) are always obtained from onefourth of n×n of electron detection parts. Photoelectron incidenceposition is calculated by inversion (for example, the Hadamartinversion) from the obtained data, and the position of the photonsincident on the photoelectric conversion part can be obtained.Accordingly, two-dimensional weak radiation can be two-dimensionallydetected at a high speed with high precision, and a two-dimensionalscreen image by weak radiation can be obtained.

The energy of the incident photon is obtained based on the magnitude ofthe output signal of the electron detection part, and the output signalis converted into the previously given color signal correspondingly tothe energy, whereby when a photon of any wavelengths is inputted, it ispossible to make the image of the weak radiation, which is obtainedtwo-dimensionally, a color image, thus making it possible to recognizeand understand the state of the two-dimensional weak radiation moreeasily. Further, color night vision cameras and the like can be easilyformed.

If the magnitude of the output signal of the electron detection part isobtained based on the repetition frequency of the output pulse signal,which the electron detection part outputs, an error caused byfluctuations in measurement can be avoided, and the magnitude of theoutput signal to be detected can be obtained easily and reliably. If theemission part, which emits photons by the incidence of electromagneticwaves or corpuscular rays, is provided at the front of the photoelectricconversion part, weak X-rays and γ-rays, α rays and the like can bedetected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a two-dimensional weak radiation detectoraccording to an embodiment of the present invention;

FIG. 2 is an explanatory view of a detail of a detection part accordingto the embodiment;

FIG. 3 is a perspective view showing an outline of the detection partaccording to the embodiment;

FIG. 4 is a perspective view explaining a two-dimensional receiverconstituting the detection part according to the embodiment;

FIG. 5 is an explanatory view of a detail of a microcapillary accordingto the embodiment;

FIG. 6 is an explanatory diagram of a detail of a detection moduleaccording to the embodiment;

FIG. 7-a is a diagram explaining a state of an output pulse of a dataread part according to the embodiment;

FIG. 7-b is a diagram explaining a state of the output pulse of the dataread part according to the embodiment;

FIG. 7-c is a diagram explaining a state of the combined output pulse ofthe data read part according to the embodiment;

FIG. 8 is an explanatory diagram of a method for controlling anoperation of a detection module according to the embodiment;

FIG. 9 is an explanatory diagram of the output pulse, which the dataread part according to the embodiment outputs;

FIG. 10 is an explanatory diagram of an energy spectral based on theoutput pulse of the data read part according to the embodiment; and

FIG. 11 is an explanatory view of a conventional DNA chip reader.

BEST MODE FOR CARRYING OUT THE INVENTION

A preferred embodiment of a two-dimensional weak radiation detectoraccording to the present invention will be explained in detail accordingto the accompanying drawings.

FIG. 1 is a schematic block diagram of the embodiment of thetwo-dimensional weak radiation detector according to the presentinvention, and shows an example in which it is applied to a DNA chipreader. In FIG. 1, a weak light detector 40 that is the two-dimensionalweak radiation detector has a laser radiation unit 42. The laserradiation unit 42 makes it possible to irradiate a DNA chip 46 to be aspecimen, which is placed on an inspection stage 44, with a laser beam50 via a lens system 48. The weak light detector 40 includes a detectionunit 52 placed above the inspection stage 44, and a signal processingunit 54 which obtains positions of cells creating a hybrid, and the likein the DNA chip 46 based on an output signal of the detection unit 52.

The detection unit 52 is constituted by a detecting part 56 including alarge number of microcapillaries which detect weak light, and anoperation control part 58 which operates the detecting part 56. Thesignal processing unit 54 has a data read part 60 reading an outputsignal of the detecting part 56. Further, the signal processing unit 54has an amplitude detection part 62, which is connected to an output sideof the data read part 60, a counting part 64, which is provided at anoutput side of the amplitude detection part 62, an image creation part68 into which a signal from the counting part 64 is inputted, and anoutput part 70, which is provided at an output side of the imagecreation part 68. The image creation part 68 is formed by an imagecalculation part 68 a and a spectral creation part 68 b of which actionswill be described later. A display device 74 and a printer 72, whichserve as output devices, an external memory 76 and the like areconnected to the output part 70.

The detecting part 56 of the detection unit 52 includes a lens 80, aphotoelectric conversion part 82, a microchannel plate 84 to be anamplification module, and a detection module 86 as shown in FIG. 2, andthe lens 80 is a detection window. The detection part 56 is providedwith a light shielding container 56 a which shields the laser beam 50and extraneous light, and the lens 80 is attached to a front end surfaceof this light shielding container 56 a, as shown in FIG. 3. Further, thephotoelectric conversion part 82, the microchannel plate 84, and thedetection module 86 are placed behind the lens 80 in this order insidethe light shielding container 56 a. The photoelectric conversion part82, the microchannel plate 84, and the detection module 86 constitute anultra-high speed photon counting type two-dimensional receiver 56 b. Anoptical filter 56 c is placed between the lens 80 and thetwo-dimensional receiver 56 b. The optical filter 56 c shields afrequency band of laser light and selectively transmits light that is inthe frequency band corresponding to fluorescence to allow the light tobe incident on the two-dimensional receiver 56 b.

The two-dimensional receiver 56 b has a vacuum container 56 d as shownin FIG. 4, and the photoelectric conversion part 82 is attached to aback side of a front face of the vacuum container 56 d. Themicrochannerl plate 84 and the detection module 86 are placed inside thevacuum container 56 d. In the two-dimensional receiver 56 b, thephotoelectric conversion part 82, the microchannel plate 84, and thedetection module 86 are placed to be in close contact with each other.

The detection part 56 is placed so that the lens 80 faces the DNA chip46. The lens 80 allows fluorescence which is emitted by the cell of theDNA chip 46 to form an image on the photoelectric conversion part 82.When a fluorescence (photon) 88 transmitted through the lens 80 and theoptical filter 56 c is incident on the photoelectric conversion part 82,the photoelectric conversion part 82 emits an electron (photoelectron)90. The electron 90, which the photoelectric conversion part 82 emits,is amplified to be about 10⁵ to 10⁷ times in number in the microchannelplate 84, the detail of which will be described later, to be anamplified electron 92, and is incident on the detection module 86 to bedetected by the detection module 86.

The microchannel plate 84 has a constitution in which a large number ofmicrocapillaries 94, which are secondary electron multipliers, areplaced in a matrix form to face the cells of the DNA chip 46. Themicrocapillary 94 constituting the microchannel plate 84 is constitutedby an accelerating tube 96 with the diameter of 5 μm to 20 μm and thelength of about 0.1 mm to 1.0 mm, and a cathode 98 and an anode 100which are provided at both ends of the accelerating tube 96, as shown inFIG. 5. In the microcapillary 94, the cathode 98 and the anode 100 areconnected to a direct-current power supply 102, and a direct-currenthigh voltage of 1000 to 10000V is applied between the cathode 98 and theanode 100. As a result, the electron 90, which is incident on the insideof the accelerating tube 96 from the side of the cathode 98, isaccelerated by the high voltage applied between the cathode 98 and theanode 100, and each time the electron 90 collides against an inner wallof the accelerating tube 96, it generates secondary electrons to beamplified to surge in number, which are emitted from the side of theanode 100 as the amplified electrons 92.

The detection module 86 is as shown in FIG. 6. Namely, the detectionmodule 86 includes a number of detection transistors 104 (104 _(ij))constituted by MOS transistors and a number of read transistors 106 (106a, 106 b, 106 c . . . ) constituted by the MOS transistors. n×n of thedetection transistors 104 _(ij) (i=1, 2, 3, . . . n, j=1, 2 3, . . . n)are placed in the matrix form corresponding to the microchapillaries 94constituting the microchannel plate 84. n of the read transistors 106are provided to correspond to each column of the detection transistors104 which are placed in the matrix form.

At each line of the detection transistors 104, gates are connected to agate control line 108 (108 a, 108 b, 108 c, . . . ), and these gatecontrol lines 108 are connected to a gate switching circuit 110constituting the operation control part 58. At each column of thedetection transistors 104, drains are connected to a source of the readtransistor 106 via a data line 112 (112 a, 112 b, 112 c, . . . ). Ateach of the read transistors 106, a drain is connected to the data readpart 60 of the signal processing unit 54, and each gate is connected toa corresponding read line 114 (114 a, 114 b, 114 c, . . . ). Detectionelectrodes 120 provided to face an output side of the microcapillary 94are connected to sources of the detection transistors 104.

Each of the read lines 114 is connected to a read line switching circuit116 constituting the operation control part 58. The operation controlpart 58 is constituted by the gate switching circuit 110, the read lineswitching circuit 116, a switching control part 118 and the like. Theswitching control part 118 generates a switching control signal based ona binary orthogonal modulation pattern as the detail will be describedlater, and it gives the switching control signal to the gate switchingcircuit 110 and the read line switching circuit 116, so that each of thedetection transistors 104 and each of the read transistors 106 areswitched to operate based on the orthogonal modulation pattern.

An operation of the weak light detector 40 according to the embodimentwhich is constituted as above is as follows. First, the DNA chip 46which creates a hybrid with a sample not shown is placed on theinspection stage 44, and the entire DNA chip 46 is irradiated with thelaser beam 50 by the laser radiation unit 42. If the cell of the DNAchip 46 creates a hybrid with the DNA of the sample labeled with afluorescent material, the cell emits fluorescence. This fluorescence(photon) is incident on the detection part 56 of the detection unit 52provided above the inspection stage 44.

The photon 88 which is incident on the detection part 56 is transmittedthrough the lens 80 and converted into an electron (photoelectron) 90 bythe photoelectric conversion part 82, as shown in FIG. 2. The electron90 is incident on the amplifying tube 96 of the microcapillary 94constituting the microchannel plate 84 (see FIG. 5). When the electron90 enters the amplifying tube 96, it is accelerated by a high directcurrent voltage applied at both ends of the amplifying tube 96, thencollides against the inner wall of the accelerator tube 96 many times togenerate the secondary electrons, and the number of it is amplified byabout 10⁵ to 10⁷ times. The amplified electrons 92 are incident on thedetection electrodes 120 of the detection module 86 and electricallycharge the detection electrodes 120. Accordingly, the detectiontransistors 104 are successively switched to operate, whereby it isknown which detection transistors 104 have the detection electrodes 120that the amplified electrons 92 are incident on.

Incidentally, the fluorescence emitted by the cell of the DNA chip 46 isextremely weak, and the electron 90 generated by the photoelectricconversion is only rarely incident on each of the microcapillaries ofthe micro channel plate 84. Namely, the amplified electrons 92 are onlyrarely incident on each of the detection electrodes 120 of the detectionmodule 86. Consequently, when data is read out by selecting one gatechannel (one gate control line 108) and one read channel (one readcontrol line 114), the data read part 60 outputs a detection pulse 122only sparsely. In addition, since the gate control line 108 and the readcontrol line 114 are successively switched, n×n times of switching arerequired, and if the number of n is 100 to 1000 (the number of cells isten thousands to one million), tremendous reading time is required.

Thus, when a number of gate control lines 108 and one of the readcontrol lines 114 are selected and a number of detection transistors 104are driven at the same time, more pulses 124 than when the detectiontransistors 104 are individually driven can be obtained for each of thedata lines 112 as shown in FIG. 7-b. When the data read part 60 outputsa pulse train which is formed by combining signals of a number of readlines, the density of the detection pulse 122 in time sequence can bemade high, as shown in FIG. 7-c. However, if things continue the waythey are, it cannot be known the output of which detection transistor104 provides the detection pulse 122, and therefore a two-dimensionalimage of the photon emission cannot be obtained, thus making itimpossible to determine which cell of the DNA chip 46 creates thehybrid. Consequently, in this embodiment, a driving signal based on theorthogonal modulation pattern is generated and thereby the detectiontransistor 104 is driven.

As the orthogonal modulation pattern described above, a modulationpattern corresponding to each line of a Hadamard matrix, which is abinary orthogonal modulation pattern, is suitable. The Hadamard matrixis constituted by elements of “+1” and “−1”, and is a symmetric matrixin which the elements at the symmetrical positions along the diagonalline are the same. For example, when a first order Hadamard matrix H⁽¹⁾is written in concrete, it is as follows. $\begin{matrix}{H^{(1)} = \begin{bmatrix}1 & 1 \\1 & {- 1}\end{bmatrix}} & \left\lbrack {{Formula}\quad 1} \right\rbrack\end{matrix}$A second order and third order Hadamard matrixes H⁽²⁾ and H⁽³⁾ can bewritten as formula 2 and formula 3. $\begin{matrix}{H^{(2)} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & {- 1} & 1 & {- 1} \\1 & 1 & {- 1} & {- 1} \\1 & {- 1} & {- 1} & 1\end{bmatrix}} & \left\lbrack {{Formula}\quad 2} \right\rbrack \\{H^{(3)} = \begin{bmatrix}1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 \\1 & {- 1} & 1 & {- 1} & 1 & {- 1} & 1 & {- 1} \\1 & 1 & {- 1} & {- 1} & 1 & 1 & {- 1} & {- 1} \\1 & {- 1} & {- 1} & 1 & 1 & {- 1} & {- 1} & 1 \\1 & 1 & 1 & 1 & {- 1} & {- 1} & {- 1} & {- 1} \\1 & {- 1} & 1 & {- 1} & {- 1} & 1 & {- 1} & 1 \\1 & 1 & {- 1} & {- 1} & {- 1} & {- 1} & 1 & 1 \\1 & {- 1} & {- 1} & 1 & {- 1} & 1 & 1 & {- 1}\end{bmatrix}} & \left\lbrack {{Formula}\quad 3} \right\rbrack\end{matrix}$

Namely, the Hadamard matrix can be defined by the following recurrenceformula. $\begin{matrix}{{H^{(0)} = 1},{H^{(k)} = \begin{bmatrix}H^{({k - 1})} & H^{({k - 1})} \\H^{({k - 1})} & {- H^{({k - 1})}}\end{bmatrix}}} & \left\lbrack {{Formula}\quad 4} \right\rbrack\end{matrix}$It should be noted that in formula 4, k represents the degree.

Thus, in the embodiment, the switching control part 118, whichconstitutes the operation control part 58 of the detection unit 52,creates a switching operation signal for the detection transistor 104based on the Hadamard matrix which corresponds to “+1” of the case inwhich the switch is turned on, and “−1” of the case in which the switchis turned off, and the switching control part 118 gives it to the gateswitching circuit 110 and the read line switching circuit 116 as aswitching control signal. For example, when the detection module 86 isconstituted by 8×8 of the detection transistors 104, the operationsignal for the detection transistors 104 is as shown in FIG. 8. Thediagonally shaded areas correspond to +1 which is turned on by beinggiven the operation voltage, and the open areas correspond to −1 whichis turned off.

Namely, the switching control part 118 gives the switching controlsignal according to the Hadamard matrix to the gate switching circuit110, then it applies the gate voltage to the gate of each of thedetection transistors 104 via the gate control line 108 by switching thegate voltage according to the Hadamard matrix, and gives the switchingsignal based on the Hadamard matrix to the read line switching circuit116 to switch the read transistors 106 according to the Hadamard matrixto operate them. For example, when the number of the detectiontransistors 104 is 8×8, the switching control part 118 creates 8modulation modes shown in the lower part of FIG. 8 based on the Hadamardmatrix, first gives the operation signal of zero order (switchingsignal) shown in the right side of the lower part of FIG. 8 to the gateswitching circuit 110, connects all the gate control lines 108 to a gatepower supply, applies gate voltage to the gates of all the detectiontransistors 104, gives the switching signals of zero order to theseventh order in the left side of the lower part of FIG. 8 to the readline switching circuit 116, and by doing so successively switches theread transistors 106 based on the Hadamard matrix to drive them.

When switching of the 0 order to the seventh order is finished for theread transistors 106, the switching control part 118 gives the drivesignal of the first order to the gate switching circuit 110, and appliesvoltage to the gates of the detection transistors 104 connected to thegate control line 108 a in the first, the third, the fifth and theseventh lines, in which state the transistors 106 are switched to thezero order to the seventh order. In this manner, the switching controlpart 118 switches the read transistors 106 from the zero order to theseventh order each time it switches the voltage which is applied to thegates of the detection transistors 104 from the zero order to theseventh order. As a result, the gate voltage is always applied to a halfof the detection transistors 104, a half of the data lines 112 are on,and the output signals are inputted into the data read part 60 from anone forth of the total number of the detection transistors 104.

The data read part 60 converts currents, which are inputted as theoutput signals of the detection transistors 104, into voltage to amplifythem, and outputs the output pulse 130 as shown in FIG. 6 as voltage.The output pulse 130 is inputted into the amplitude detection part 62 ofthe signal processing unit 54 as shown in FIG. 1. The output pulse 130of the data read part 60 may be subjected to A/D conversion.

When the gates of the detection transistors 104 are switched based onthe Hadamard matrix and voltage is applied to them and the readtransistors 106 are switched according to the Hadamard matrix to operatethem, demodulation is performed with use of the Hadamard inversion fromthe pulse 130 (data modulated based on the Hadamard matrix) outputted bythe data read part 60, whereby the detection transistor 104 whichoutputs the pulse 130 can be obtained. Namely, when the pulse repetitionfrequency data matrix with the gate control line 108 as a row and withthe read control line 114 (data line 112) as a column is considered, theHadamard inversion (two-dimensional Hadamard inversion) is performed inthe row direction and the column direction, whereby pulse repetitionfrequency of the detection transistor 104 by the combination of one ofthe gate control lines 108 and one of the read control lines 114, whichare optionally selected, can be determined. Accordingly, the imagecalculation part 68 a is an incident position calculating part as thedetail will be described later, and the Hamadard inversion is performedbased on the data of the counting part 64, whereby the detectiontransistor 104 on which the amplified electron 92 is incident can beobtained, the microcapillary 94 into which the photoelectron 90 isinputted can be determined, and it can be known which position of thephotoelectric conversion part 82 the photon 88 is incident on.Consequently, it can be known which cell of the DNA 46 emits thefluorescence.

The amplitude detection part 62 of the signal processing unit 54 obtainsthe amplitude (magnitude of voltage) of the pulse 130 outputted by thedata read part 60 and inputs it into the counting part 64. Namely, whena number of fluorescent materials are added to the sample not shown tobe combined with the cells of the DNA chip 46, a number of fluorescencesare emitted from the DNA chip 46 when the cells create hybrids.Accordingly, if the fluorescent materials differ, the fluorescences withdifferent wavelengths are emitted, and the energies of the photons 88incident on the photoelectric conversion part 82 differ respectively. Asa result, the electrons (photoelectrons) 90 generated in thephotoelectric conversion part 82 differ in kinetic energy due todifference in the energy of the incident photons 88, and when thefluorescence with a short wavelength is incident, the electron 90 with alarge kinetic energy is generated. When the electron 90 with a largerkinetic energy is incident on the microcapillary 94, more secondaryelectrons are generated, and the number of the amplified electrons 92becomes larger. Accordingly, the output of the detection transistor 104corresponding to the microcapillary 94, on which the electron 90 basedon the photon 88 by the fluorescence with a short wavelength isincident, becomes larger, and the amplitude of the pulse 130 (height ofthe pulse 130) outputted by the date read part 60 becomes larger.Namely, the output pulses 130 of the data read part 60 have differentamplitudes as shown in FIG. 9 when the DNA chip 46 emits a number offluorescences.

The counting part 64 reads the output signal of the amplitude detectionpart 62 in synchronism with the switching control part 118 of theoperation control part 58 outputting a switching control signal to theread line switching circuit 116, counts the pulses 130 outputted by thedata read part 60 for each amplitude obtained by the amplitude detectionpart 62, and inputs it into the image calculation part 68 a of the imagecreation part 68. The image calculation part 68 a that is the incidentposition calculation part stores the counting value outputted by thecounting part 64 in an internal memory not shown for each magnitude ofthe pulses 130 correspondingly to the readout mode of the data. When thereadout of the data according to the modulation mode based on theHadamard matrix is finished, the image calculation part 68 a reads thecounting value from the counting part 64, which is stored in theinternal memory, and performs Hadamard inversion of this data accordingto the computing equation which is given in advance. Consequently, asdescribed above, the image calculation part 68 a obtains the position ofthe detection transistor 104 which outputs the signal, namely, theposition of the microcapillary 94 on which the electron (photoelectron)90 is incident, determines the cells inside the DNA chip 46, which emitthe fluorescence, and obtains pulse repetition frequency as to themagnitude of the output pulse 130 (magnitude of the amplitude) of thedata read part 60 for each cell.

The spectral creation part 68 b constituting the image creation part 68reads the pulse repetition frequency (number of pulses) for eachamplitude of the output pulses 130 obtained by the image calculationpart 68 a, and creates an energy spectral in respect of the output pulse130 for each pixel as shown in FIG. 10. Further, the spectral creationpart 68 b obtains the energy (wavelength of fluorescence) of the photonwhich is incident on the detection unit 52 based on the created energyspectral. Namely, the spectral creation part 68 b obtains wavelengthsλ₁, λ₂ and λ₃ of the fluorescence corresponding to maximum values a, band c of the pulse repetition frequencies in FIG. 10 from the functionalrelationship between the wavelength of the fluorescence and theamplitude of the output pulse 130 of the data read part 60, and itselects the color which is given in advance to the wavelength λ toconvert it into a color signal. In this situation, the wavelengthconversion part 68 b changes the depth of the color (magnitude of thecolor signal) according to the number (frequency) of the pulses in FIG.10. The color signal which is outputted by the spectral creation part 68b is outputted to the display device 72 and the like via the output part70. As a result, the cells creating the hybrids of the DNA chip 46 aredisplayed as ordinary two-dimensional color images. Consequently, weakradiation of fluorescence or the like which is two-dimensionally emittedcan be detected at a high speed with high precision, and atwo-dimensional image by weak radiation can be obtained. A peak dcorresponding to the area with the wavelength λ of zero corresponds to anoise.

In the aforementioned embodiment, the explanation is made about the casein which the detection part 56 is constituted by the lens 80, thephotoelectric conversion part 82, the microchannel plate 84, and thedetection module 86, but an emission part such as a scintillator may beprovided at the front of the lens 80. By providing the emission partlike this, very weak electromagnetic waves and corpuscular rays, such asX-rays, γ-rays, electron rays and α-rays can be two-dimensionallydetected and visualized.

The embodiment explained above is the explanation of one mode of thepresent invention, and the present invention is not limited to this. Forexample, in the aforementioned embodiment, the explanation is made aboutthe case in which the present invention is applied to the detection ofthe cells creating hybrids of the DNA chip 46, but it can be used as acolor night vision camera.

As explained thus far, according to the present invention, a number ofelectron detection parts constituting the detection module are operatedaccording to the orthogonal modulation pattern (for example, the patterncorresponding to each line of the Hadamard matrix), then the outputsignals (data) are always obtained from one fourth of n×n of electrondetection parts, and inversion of the data is performed with respect tothe obtained output signals in the incident position calculation part,whereby the electron detection parts which output the output signals canbe determined, and the position of the photons incident on thephotoelectric conversion part can be obtained. Accordingly,two-dimensional weak radiation can be two-dimensionally detected at ahigh speed with high precision, and a two-dimensional visual image byweak radiation can be obtained.

In the present invention, the energy of the incident photon is obtainedbased on the magnitude of the output signal of the electron detectionpart, and the output signal is converted into the color signal, which isgiven in advance, correspondingly to the energy, and therefore it ispossible to make the image of the weak radiation, which is obtainedtwo-dimensionally, a color image, when photons based on light with anumber of wavelengths are inputted, thus making it possible to recognizeand understand the state of the two-dimensional weak radiation moreeasily.

In the present invention, the magnitude of the output signal of theelectron detection part is obtained based on the frequency of the outputsignal which the electron detection part outputs, thus making itpossible to avoid an error caused by fluctuations in measurement andobtain the magnitude of the output signal to be detected easily andreliably. Since the emission part, which emits photons by the incidenceof electromagnetic waves or corpuscular rays, is provided at the frontof the photoelectric conversion part, it is possible to detect weakX-rays and γ-rays, α rays and the like.

INDUSTRIAL AVAILABILITY

The present invention can be utilized for a two-dimensional weakradiation detector which detects weak microwaves and corpuscular rays,which are two-dimensionally radiated.

1. A two-dimensional weak radiation detector, comprising: aphotoelectric conversion part which emits electrons by incidence ofphotons; an amplification module which is placed to face thephotoelectric conversion part, and is provided with a number of electronamplification parts that amplify the electrons emitted by thephotoelectric conversion part; a detection module which is provided tocorrespond to each of said electron amplification parts constituting theamplification module, and is provided with a number of electrondetection parts on which the electrons from the electron amplificationparts are incident; an operation control part which operates each ofsaid electron detection parts constituting the detection module based onan orthogonal modulation pattern; and a light incidence positioncalculation part which obtains positions of said photons incident onsaid photoelectric conversion part, based on a control signal of theoperation control part and an output signal of each of said electrondetection parts.
 2. A two-dimensional weak radiation detector,comprising: a photoelectric conversion part which emits electrons byincidence of photons; an amplification module which is placed to facethe photoelectric conversion part, and is provided with a number ofelectron amplification parts that amplify the electrons emitted by thephotoelectric conversion part; a detection module which is provided tocorrespond to each of said electron amplification parts constituting theamplification module, and is provided with a number of electrondetection parts on which the electrons from the electron amplificationparts are incident; an operation control part which operates each ofsaid electron detection parts constituting the detection module based onan orthogonal modulation pattern; a light incidence position calculationpart which obtains positions of said photons incident on saidphotoelectric conversion part, based on a control signal of theoperation control part and an output signal of each of said electrondetection parts; and a wavelength calculation part which obtains energyof said photons based on magnitude of the output signal of each of saidelectron detection parts, and converts it into a color signal.
 3. Thetwo-dimensional weak radiation detector according to claim 2, whereinsaid wavelength calculation part obtains the magnitude of the outputsignal based on output pulse repetition frequency of the output signalof said electron detection part and converts it into said color signal.4. The two-dimensional weak radiation detector according to claim 1,wherein an emission part, which emits photons by incidence of microwavesor corpuscular rays, is provided at a front of said photoelectricconversion part.